Skip to content


Grammarflex logo

What’s the Plural of Addendum?

Addendum has two plural noun forms: both addenda and addendums are correct, though the former is the original Latinate pl. n. form.

What’s the plural of “addendum”?

The plural of an addendum is addenda and addendums. An addendum, which is “something that has been added to a book, speech, or document”, is synonymous with appendix or supplementary material. Typically, addenda will include notes or material missing from the main text or work.

Addendum has two plural noun forms: both addenda and addendums are correct, though the former is the original Latinate pl. n. form.  Addendums, on the other hand, uses the standard pl. n. modifier in English by adding the –s at the end to show a plural. This standard form most likely came to be adopted as a plural for addendum over time, and through the consistent mistaking of addendums as the plural form.

Irregular plural nouns that end in um-/-a

Though unusual, addendum is by no means the only Latin noun that has sustained until Modern English. See the chart of irregular nouns that end in -um as a singular noun, and convert to -a as a plural:

colloquiumcolloquia or colloquiums
referendumreferenda or referendums
memorandummemoranda or memorandums
curriculumcurricula or curriculums
addendumaddenda or addendums
symposiumsymposia or symposiums

Addendum in context (in sentences)

1. Alex added some personal remarks in the addendum of his letter.

2 .Maria’s article was written in 1965, but it was updated with an addendum in recent years.

3. I added an addendum to the report in which I highlighted certain legal issues that our company was facing.

4. It would be smart to add an addendum to your resume to highlight some of your areas of expertise.

5. If you read the addendum to Oliver’s biography, you will learn about the lesser known aspects of his life.

Addenda/addendums in context (in sentences)

1. “We want to address the new addenda of the CMO,” said Glen Hartman, head of Accenture Interactive North America.

2. Make sure the lease contains signatures by both parties and all amendments, addenda, renewals, etc., are located and included. –OC Register

3. The lawyers introduced various addenda to the contract.

4. This includes the table of contents and any attachments or addenda .

5. They are extraneous addenda , and insidious ones at that.

Addendum synonyms

Origin of the word addendum

From etymonline on addendum, from Latin addendum, neuter of addendus “that which is to be added”.


What’re personal pronouns?

What’s the difference between they’re, their, and there?

Whose vs who’s?


  1. Synonyms of addendum.
  2. Origin of addendum
  3. Definition of addendum

Recent Posts